306.3 🏥 內科專科考前版

306.3.1 Mechanistic Deep Dive

306.3.1.1 HP Pathophysiology

  • Type III (immune complex) — acute
  • Type IV (delayed cell-mediated) — subacute, chronic
  • Th1 response (in non-fibrotic) → granulomatous inflammation
  • Th2 shift in chronic → fibrosis
  • Genetic susceptibility (MHC II alleles)

306.3.1.2 Fibrotic HP Mechanism

  • Persistent antigen exposure or genetic susceptibility
  • Pro-fibrotic cytokines (TGF-β)
  • Fibroblast activation, ECM deposition
  • Antifibrotic agents (nintedanib, pirfenidone) target this

306.3.2 Recent Trials & Updates

306.3.2.1 INBUILD (2019) — Nintedanib for Progressive Fibrotic ILD

  • HP + other progressive fibrotic ILD
  • Nintedanib slowed FVC decline
  • FDA approved for progressive pulmonary fibrosis 2020
  • Expanded use in fibrotic HP

306.3.2.2 2020 ATS/JRS/ALAT HP Guidelines

  • Updated classification: fibrotic vs non-fibrotic
  • Treatment recommendations
  • Antifibrotic for fibrotic HP

306.3.2.3 ISHAM 2022 ABPA Update

  • Refined diagnostic criteria
  • Total IgE > 500 (relaxed from 1000)
  • Imaging + immunology

306.3.2.4 MEPACATA (2024) — Mepolizumab in HES

  • Confirmed efficacy
  • Reduced flares + steroid dependence

306.3.2.5 Dupilumab for ABPA (2024)

  • Phase 2/3 trials
  • For refractory cases
  • IL-4Rα blockade

306.3.2.6 Tezepelumab for Eosinophilic Conditions

  • Trials in CEP, ABPA, hypereosinophilia
  • Broader efficacy

306.3.3 High-Yield Specialist Points

306.3.3.1 Pigeon Breeder’s Lung Pearls

  • Specific avian protein (mucin, IgA, IgG)
  • Even brief exposure (cleaning coop)
  • “Pigeon breeder’s lung” or “bird fancier’s”
  • Specific precipitins
  • Avoidance often curative for non-fibrotic

306.3.3.2 Hot Tub Lung

  • MAC (Mycobacterium avium complex) aerosolized
  • Immune-mediated rather than infection alone
  • Drain + treat hot tub OR remove
  • Steroids + antimicrobial in some

306.3.3.3 Farmer’s Lung (Saccharopolyspora rectivirgula)

  • Moldy hay
  • Thermophilic
  • Seasonal
  • Industrial farming reduced incidence
  • Mask + ventilation prevention

306.3.3.4 CD8+ HP vs CD4+ Sarcoid

  • HP: typically CD8 predominant
  • Sarcoid: CD4 predominant
  • Older teaching; some overlap

306.3.3.5 Eosinophilic Pulmonary HRCT Patterns

  • CEP: peripheral + upper lobe (“photographic negative of pulmonary edema”)
  • AEP: diffuse ground-glass + bilateral infiltrates
  • ABPA: central bronchiectasis + mucus impaction
  • EGPA: variable; nodules, ground-glass, consolidation

306.3.3.6 ABPA Stages (Rosenberg-Patterson)

  1. Acute
  2. Remission
  3. Exacerbation
  4. Corticosteroid-dependent
  5. End-stage fibrosis

306.3.3.7 ABPA Treatment Pearls

  • Itraconazole reduces steroid dose
  • Voriconazole alternative
  • Posaconazole emerging
  • Dupilumab for refractory (case reports + emerging trials)
  • Aspergillus eradication challenging

306.3.3.8 EGPA Diagnosis

  • Asthma (often severe)
  • Peripheral eosinophilia (> 10%)
  • Mono / polyneuropathy
  • Pulmonary infiltrates
  • Paranasal sinus abnormality
  • Extravascular eosinophils on biopsy

306.3.3.9 EGPA Treatment

  • Steroids (always)
  • Cyclophosphamide (severe with vasculitis)
  • Rituximab (alternative for ANCA-positive)
  • Mepolizumab (Class I; reduces flares)
  • Plasmapheresis for ANCA-positive vasculitis

306.3.3.10 Drug-Induced Eosinophilic Pneumonia

  • Common drugs: NSAIDs, antibiotics (nitrofurantoin, sulfa), antiarrhythmics (amiodarone), immunotherapy
  • Stop drug; steroids if severe
  • Recovery usually complete

306.3.3.11 Loeffler Syndrome

  • Transient pulmonary infiltrates + eosinophilia
  • Parasites (Ascaris larvae migrating through lungs)
  • Self-limited
  • Anti-parasitic + bronchodilator if symptomatic

306.3.3.12 Idiopathic HES — FIP1L1-PDGFRA

  • Imatinib responsive (myeloid HES)
  • Less common subtype
  • Other variants: lymphocytic (T-cell driven), Multi-organ

306.3.3.13 CT-Guided HP Workup

  • Detailed history
  • HRCT (expiratory + prone protocols)
  • BAL cell differential
  • Specific precipitins
  • Cryobiopsy if uncertain
  • Multidisciplinary discussion

306.3.4 Pearls

  • HP classification: fibrotic vs non-fibrotic (2020 ATS)
  • HP BAL: lymphocytosis, CD4/CD8 < 1
  • HP HRCT: mosaic attenuation + centrilobular nodules; fibrotic = upper-mid lung
  • HP treatment: antigen avoidance + steroids + antifibrotic for fibrotic (INBUILD)
  • AEP: smoking trigger + BAL eos > 25%; dramatic steroid response
  • CEP: “photographic negative” HRCT + asthma; relapse 50%
  • ABPA: asthma/CF + IgE > 1000 + central bronchiectasis; itraconazole + steroids; dupilumab emerging
  • EGPA: asthma + eosinophilia + vasculitis; mepolizumab Class I
  • HES: > 1500 eos + 6 mo + organ; imatinib if FIP1L1-PDGFRA